摘要:随着人口增长对粮食需求的不断提高，人类对自然生态系统扰动频繁，生态覆被/土地利用变化伴随着土壤活性氮库、氮形态组分及氮素内循环过程的改变，直接影响生态系统的持续与稳定，进而引起全球气候变暖，生物多样性减少等诸多生态环境问题。生态覆被/土地利用变化是全球生态系统变化的重要内容。本综述探讨了活性氮的基本概念及其引发的环境效应，国内外自然生态系统中森林与草地间转换、自然生态系统开垦为农田、弃耕撂荒或退耕还林还草、城市化发展等生态覆被/土地利用变化对土壤氮库消长、氮矿化产物形态变化以及影响氮循环的关键土壤微生物影响等，并探讨了制约氮循环的土壤微生物研究进展。指出农业开垦或农田弃耕撂荒会导致土壤全氮大幅度下降，同时引起土壤硝态氮（NO3--N）增加，造成环境活性氮增加的风险；退耕还林修复生态覆被过程中氮库完全恢复需要漫长的时间；运用现代微生物分子生态学的前沿技术是研究土壤氮循环对生态覆被/土地利用变化响应机理的关键。本综述为自然生态系统的保护与开发利用、退化生态系统的修复与重建以及人工生态系统的科学规划等提供了理论依据。
关键词:生态覆被/
土地利用变化/
活性氮/
氮转化/
土壤微生物
Abstract:Soil nitrogen (N) pool and its' cycles is directly related to crop growth, ecological environment security, and sustainable development. Soil N and carbon storage in natural ecosystems is relatively stable, with a low net mineralization and a closed or accumulative cycle. In order to meet the demand from the growing population for food production and living space, humans frequently modify natural ecosystems, resulting in changes to land use and ecological cover, which significantly change the soil active N content and N cycles, thereby affecting global climate change and the natural environment. In the face of threats from global warming, reduction of biodiversity, and ecological degradation, this paper reviewed the impact of soil active N on the environment, N storage, and N cycling process, including mineralization, nitrification, and fixation, caused by land use change. We considered the transformation, deforestation, afforestation, or reconstruction of ecosystems, as well as progress in research methods on microorganisms in the N cycle. Our review showed that agricultural reclamation or disturbance — the conversion of natural ecosystems into farmland or the abandonment of farmland that was originally forest or grassland — would lead to a significant decrease in total N, but an increase in the nitrate (NO3--N) content, which increases the risk of active N in the environment. Reforestation provides an alternative approach for the reconstruction of ecological cover, but full restoration of the N pool will take decades. It seems that the application of modern microbial molecular ecology is the key to research the response mechanism of the soil N cycle to ecological cover/land use change. The aim of this review was to provide a scientific basis for the protection and use of native ecosystems, the restoration and reconstruction of degraded ecosystems, scientific planning and policy-making for artificially disturbed ecosystems by understanding the effects of land use change on the soil N pool, coupled N cycling, and the soil microbial community structure.
Key words:Ecosystem cover/
Land use change/
Active N/
Nitrogen cycling/
Soil microbe
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